Volume 17, Number 2, 2015
© WIETE 2015
Global Journal of Engineering Education
The evaluation of a new hybrid flipped classroom approach to teaching power
electronics
H. Bora Karayaka & Robert Adams
Western Carolina University
Cullowhee, NC, Unite States of America
ABSTRACT: Developing an emphasis in electric power engineering plays a vital role in educating the next generation
of southeastern US power industry workforce. To that end, a curriculum development effort was planned and is
projected to train, prepare for research and educate students enrolled in the Department of Engineering and Technology
at Western Carolina University for careers in the power industry. This article describes in detail the first three pilot
implementations of the Power Electronics course, which is an integral part of the curriculum for Electrical Engineering
(EE) undergraduates, and presents its assessment results, which are based on end of year survey data of three
consecutive year course offerings. The new pedagogical concept that was used is called Hybrid or Partially Flipped
Classroom Pedagogy in which active student engagement is facilitated through both on-line and face-to-face lecture
methods. In addition, this approach included a short on-line quiz before each course module and a short quiz at the start
of class session after each course module to improve student participation.
Keywords: Hybrid flipped classroom pedagogy, power electronics, electrical engineering education, workforce
development
INTRODUCTION
Growing the demand of electrical energy from sustainable sources requires a skilled workforce that is educated and
trained to take the lead on the main sub-tasks of generation, transmission and distribution and utilisation. In addition, it
has been projected that the current power industry will soon be facing a manpower crisis due to attrition within its soonto-be-retiring workforce. In a survey conducted at 2011, the Center for Energy Workforce Development analysis
indicates that 36% of current skilled technical and engineering positions in all US utilities (excluding positions in
nuclear) may need to be replaced due to potential retirement or attrition, with an additional 16% to be replaced by 2020
- almost 110,000 employees in positions identified as the most critical by industry [1]. The North American Electric
Reliability Corporation (NERC) in its 2007 report has also identified the aging workforce as a growing challenge to
future reliability of the electricity supply and NERC continues to support action and monitor industry progress [2].
The Need for Power Engineering Education and Teaching Methodologies
The demands of the power industry for a skilled workforce in power engineering disciplines combined with too few
educational programmes that support the power industry suggest the immediate need for the development and teaching
of courses in power engineering. In order to fill this gap in the skilled workforce, Sergeyev and Alaraje recently
described an industry-driven power curriculum in an electrical and computer engineering technology programme [3].
The primary outcome of their project was to educate a larger number of better qualified engineering technology
graduates with skills and knowledge that are current and relevant. In another recent study, Karayaka and Adams
provided their findings in a first implementation of a course designed within the context of power systems curriculum
development efforts to bridge the gaps of regional workforce needs [4]. The paper primarily highlighted the
effectiveness of student oriented project based learning.
Among the collaborative efforts, Mousavinezhad et al described the work of the Electrical and Computer Engineering
Department Heads Association with the support of the National Science Foundation in establishing a workshop series on
the issues aimed at developing educational and research programmes in this critical area of power and energy systems
within electrical and computer engineering [5]. Another collaborative effort is the Consortium of Universities for
Sustainable Power (CUSP™), which is currently offered by the research group led by Professor Ned Mohan of the
University of Minnesota, which promoted flipped classroom pedagogy. This consortium includes universities that have
come together to utilise, collectively evolve and promote the curriculum developed at the University of Minnesota -
61
Twin Cities with the help of funding from various organisations including the National Science Foundation (NSF),
Office of Naval Research (ONR), National Aeronautics and Space Administration (NASA) and the Electric Power
Research Institute (EPRI) [6].
Related to this effort, two recent studies were published by Lin et al that involve self-directed learning [7][8]. The
survey results among students in their first paper reveal that only 1/3 of the group indicated that they prepared as
instructed before coming to lectures while 1/3 never did. In addition, it was observed that many students were not ready
to meet the demands of self-directed study, which is one of the core themes of the flipped classroom approach.
According to the most recent paper by Lin et al, the students were instructed to know theories and content by watching
on-line video modules before coming to the class and solve problems with peers inside the classroom [8]. However,
flipping lectures has not been universally embraced due to the concerns about perceived limited contacts and
interactions between instructors and students [9].
A US Department of Education report, issued in 2010, concluded that Instruction combining online and face-to-face
elements had a larger advantage relative to purely face-to-face instruction than did purely online instruction [10]. This
report targeted a broad population including K-12, career technology, medical and higher education, as well as corporate
and military training. In addition, many studies in this report did not attempt to equate a) all the curriculum materials; b)
aspects of pedagogy; and c) learning time in the treatment and control conditions.
The study presented in this article is unique in a sense that a hybrid approach, which flips lectures partially so as to
provide the basics of theories and content in the classroom, as well as instructing students to watch on-line video
modules ahead of face-to-face session was implemented. Interactive problem-solving and Q&A still comprised a good
part of the classroom activities. Preliminary findings of this study are presented in Karayaka and Adams [11].
TEACHING THE POWER ELECTRONICS COURSE
The Power Electronics course was designed to support sustainable power engineering initiatives, such as CUSP™. This
course provides the basics of switch mode power electronics, which are important concepts for currently growing
renewable energy, smart power grid and transportation electrification industries. This course is a standard three-credithour lecture course and is offered to senior level electrical engineering students.
Student Enrolment Figures and Background
The Department of Engineering and Technology with an undergraduate enrolment close to 600 students at Western
Carolina University includes four undergraduate majors as listed below:
•
•
•
•
Bachelor of Science in Electrical Engineering (BSEE);
Bachelor of Science in Engineering Technology (BSET);
Bachelor of Science in Electrical and Computer Engineering Technology (BSECET);
Bachelor of Science in Engineering with a Mechanical Engineering (BSE-ME) concentration.
The first three majors are well established, ABET-accredited, and have been serving the region for many years. The
BSE programme is a new programme that was added in Fall 2012 with an ME concentration. In addition, two other
specialisations are scheduled to be launched in Fall 2015:
•
•
Bachelor of Science in Engineering with an Electric Power Engineering (BSE-EPE) concentration;
Bachelor of Science in Engineering with a Manufacturing Engineering (BSE-MFE) concentration.
In addition to the undergraduate programmes indicated above, the Department also has a graduate programme, which
offers a Master of Science in Technology (MST) major.
As mentioned earlier, Power Electronics is a senior level course and is currently offered only to EE majors. Therefore,
the course enrolment and assessment data in this article only includes the EE major. Consequently, the student
demographics data are solely presented for EE majors. As of Spring 2015, the enrolment numbers for all EE majors at
Western Carolina University have an average of 22 students for each level from freshman to senior. For the Power
Electronics course, the total enrolment in the first year was eight, including seven BSEE students and one MST student
all of whom are male. In the second year, the enrolment number was thirteen, including three female and nine male
BSEE students along with one female MST student. In the third year, the total enrolment was 14 students, including one
female and 12 male BSEE students along with one male MST student. The course in the discussed implementation was
offered in the Spring semesters of 2013, 2014 and 2015. Each week the class meetings were scheduled twice for the total
of three contact hours of lecture sessions.
Teaching the Power Electronics Course with a Hybrid Flipped Classroom Approach
This course was designed to introduce switch mode power electronics principles with a partially flipped (or hybrid)
classroom approach. Covered topics include analysis, design, and operation of power electronic circuits for motor drives
62
and electric utility applications, power conversion from AC to DC, DC to DC, DC to AC. In addition, design and
construction of power electronic circuits through simulations are studied. PSpiceTM software is used for power
electronics system analysis and design. Prerequisite courses include Solid State Electronic Devices and Linear Control
Systems Theory.
Required textbook:
•
N. Mohan, Power Electronics: A First Course, John Wiley & Sons, Inc., 2011.
Recommended reference book:
•
N. Mohan, T.M. Undeland and W.P. Robbins, Power Electronics: Converters, Applications, and Design, Third
Edition, John Wiley & Sons, Inc., 2003.
Course Objectives/Student Learning Outcomes (or SLOs) were designed to enable students to:
•
•
•
•
•
•
•
•
•
•
Describe the role of power electronics as an enabling technology in various applications, such as flexible
production systems, energy conservation, renewable energy, transportation, etc.
Identify a switching power-pole as the basic building block and to use pulse width modulation to synthesise the
desired output.
Design the switching power-pole using the available power semiconductor devices, their drive circuitry and driver
ICs and heat sinks. Model these circuitry in PSpiceTM.
Learn the basic concepts of operation of DC-DC converters in steady state in continuous and discontinuous modes
and be able to analyse basic converter topologies.
Using the average model of the building block, quickly simulate the dynamic performance of DC-DC converters
and compare them with their switching counterparts.
Design, using simulations, the interface between the power electronics equipment and single-phase and three-phase
utility using diode rectifiers and analyse the total harmonic distortion.
Design the single-phase power factor correction (PFC) circuits to draw sinusoidal currents at unity power factor.
Learn basic magnetic concepts, analyse transformer-isolated switch-mode power supplies and design highfrequency inductors and transformers.
Learn the requirements imposed by electric drives (DC and AC) on converters and synthesise these converters
using the building block approach.
Learn the role of power electronics in utility-related applications which are becoming extremely important.
Instructional methods and activities for instruction included both in-class and on-line lectures, homework
assignments/solutions, in-class discussions, quizzes, tests and use of simulation software.
The grading policy was determined by students’ performance in homework/simulation assignments, quizzes, midterm
and final examinations. The distribution of points for the first and second year is given in Table 1. In the third year,
homework/PSpiceTM assignment weight was reduced to 30%, and the weight for quizzes was increased to 30%.
Table 1: Grade distribution.
1.
2.
3.
4.
Homework/PSpiceTM assignments
Quizzes
Midterm examination
Final examination
40%
20%
20%
20%
Letter grades are assigned according to the following:
A+: 99-100, A: 92-98,
D+: 68-69, D: 62-67,
A-: 90-91,
D-: 60-61,
B+: 88-89,
F: 59–0.
B: 82-87,
B-: 80-81, C+: 78-79,
C: 72-77,
C-: 70-71;
In the first year implementation, although the students were made aware of pre-recorded on-line lectures through
CUSPTM, a classical in-class lecture approach was primarily emphasised. Quizzes and examinations, which both
involved problem-solving, were administered in class. However, some concept quizzes were assigned on-line and the
response was expected before coming to the class to prepare the students. Most of the lecture notes, questions used in
the examinations and the quizzes were extracted from the teaching materials provided by CUSPTM. The quizzes included
one or two questions involving either concept understanding or problem-solving. The examinations included ten to
fifteen questions with a similar question format to quizzes. In addition, the examinations had a PSpiceTM problem that
tested the student’s simulation software usage and circuit analysis skills.
In the second and third year implementation, the students were instructed to watch the pre-recorded on-line lectures for
each module before face-to-face lecture sessions. The in-class session for each module included:
63
•
•
•
Enriched CUSPTM lecture materials to provide additional information.
Sample problems and interactive solutions.
PSpiceTM simulation examples running on-site from the instructor’s computer.
After the completion of each module, a short on-line concept quiz through BlackboardTM before the next course module
and another short quiz testing problem-solving skills at the start of next class session were administered to improve
student participation. The number of quizzes was substantially larger in the second year in comparison to the first year
and this number was the largest in the third year’s implementation. Twenty four such course modules were covered
throughout the semester in Year 2, which is very similar to Year 1. Twenty one course modules were completed in
Year 3. Fewer modules were covered in Year 3, primarily because the students’ learning styles were more inquisitive
and detail oriented. As a result, the students engaged more openly in class discussions and the instructor covered the
topics in more detail. The number of simulation assignments was slightly reduced in the second year. In Year 3, the
number of simulation and homework assignments were least in comparison to the other years. The original projected
schedule of topics along with associated module sequence is given in Table 2.
Table 2: Schedule of topics for Power Electronics course.
Topic/Activity
Module
Introduction to power electronic systems
Week
1
1
Basic building block - switching power-poles
Non isolated DC-DC converters
2-4
5-11
2-3
3-6
Design of feedback controllers
12-14
6-7
Diode rectifiers
15-16
7-8
Power factor correction
17-18
8-9
19
10
20-21
11-12
22
13
23-24
14-15
Magnetic circuit concepts
Isolated switch-mode DC power supplies
Application of PE devices in motor drives, UPS and power systems
Synthesis of motor drives, UPS and power systems
The topics addressed and covered in the course in Table 2 are briefly described below:
1.
2.
Introduction to power electronics systems: role, applications and requirements are introduced.
Basic building block - switching power-poles: types of converter structures, concept of pulse width modulation,
switching power-pole circuit topology are presented. Power semiconductor devices, losses in switching powerpoles and practical considerations in designing switching power poles are introduced.
3. Non isolated DC-DC converters: operational principles of buck, boost and buck-boost converter topologies and
average models representing these topologies are introduced. Continuous and discontinuous conduction modes and
associated models are studied.
4. Design of feedback controllers: topics of regulated switch-mode power supplies, linearisation, generic control
objectives (i.e. zero steady state error, fast response, low overshoot and low noise susceptibility), and phase and
gain margin in Bode plots are covered. Voltage and current mode control principles, as well as K-factor design
approach are introduced.
5. Diode rectifiers: concepts of power factor, displacement power factor, total harmonic distortion and associated
IEEE-519 harmonic guideline are introduced. Single phase, three phase diode rectifiers and associated the nonlinear characteristics are presented.
6. Power factor correction: power factor correction using single phase rectifier and boost converter topology are
introduced. Controller design involving inner current loop control mechanism for current shaping, as well as outer
voltage loop control for output voltage regulation are studied.
7. Magnetic circuit concepts: Ampere’s circuital law, B-H curves, magnetic circuit losses (hysteresis and eddy
current), flux/flux density, reluctance, inductance, Faraday’s law and magnetic transformer topics are covered.
8. Isolated switch-mode DC power supplies: flyback, forward, full-bridge, half-bridge and push-pull converter
topologies and their operational principles are discussed.
9. Application of PE devices in motor drives, uninterruptible power supplies (UPS) and power systems: voltage and
current ratings in converters for electric machine drives (DC machine, permanent magnet AC machine and
induction machine), UPS and utility scale power system applications are presented.
10. Synthesis of motor drives, UPS and power systems: definition, average representation and pulse width modulation
of bidirectional switching power-pole are introduced. Converters for DC machine drives and associated average
representation and switching waveforms are studied. Synthesis of single phase AC systems including UPS and
photovoltaic applications are also covered.
Student assignments throughout the course flow specifically included:
64
;
•
•
•
•
•
•
•
•
PSpiceTM laboratory 1: pulse width modulation and filter characteristics;
PSpiceTM laboratory 2: switching characteristic of MOSFET and diode in a switching power-pole;
PSpiceTM laboratory 3: step-up (boost) DC-DC converter;
Homework 1: buck, boost, buck-boost converters;
Homework 2: design of feedback controllers;
Homework 3: diode rectifiers;
Homework 4: power factor correction, magnetic circuits and isolated DC power supplies;
Homework 5: application of PE devices in motor drives, UPS and power systems and synthesis of single phase AC
systems.
Homework 2 through 5 also included a PSpiceTM problem. In addition to the topics listed above, reviews before midterm
and final examination were scheduled. In these reviews, interactive sessions that involved problem-solving and concept
understanding took place. The midterm examination was also scheduled during the regular course meeting session,
which is seventy five minutes.
COURSE ASSESSMENT, RESULTS AND FINDINGS
In the final class meeting, the students were asked to complete a survey regarding the course experience and its potential
impact in their career. In Table 3, the survey results are shown, in each cell, starting with the first year result, followed
by the second and third year. Each cell has the same arrangement. As can be seen in Table 3, there were eight
respondents in the first year, 13 respondents in the second year and 14 respondents for the third year for each question.
Question 4 was not answered by one student in the third year. Each survey question had a choice varying from strongly
agree to not applicable. In the analysis, each of these options was given a weight ranging from 5 (strongly agree) to 1
(strongly disagree). Not applicable option did not have a weight factor. Table 4 presents the mean, median and standard
deviation for each survey question in each year of implementation. Question by question analysis of results is detailed in
the paragraphs that follow.
Table 3: Student survey results.
Survey question
1. Have you found the course useful to
improve your knowledge and skills on
overall electrical engineering
applications?
2. Are mathematical relationships and
calculations selected in this course
appropriate?
3. Are the computational simulation tools
(PSpiceTM) selected appropriate?
4. Do you think power electronics would
be a good tool to promote science,
technology and engineering majors
among college students?
5. Do you think you are interested to
work in electrical power related
industry after your graduation?
6. Overall quality of instruction was
appropriate and useful for this class.
7. Pre-recorded lecture videos along with
interactive face to face instruction are
effective ways to deliver course
materials and helped my
understanding.
8. On-line and in-class quizzes before and
after the lecture appropriately assessed
and improved my understanding.
9. I am interested in enrolling in future
courses of similar subject matters.
Strongly
agree
Agree
Neutral
Disagree
Strongly
disagree
Not
applicable
5/ 9 / 8
3/ 4 / 5
-/-/1
-/-/-
-/-/-
-/-/-
3/ 8 / 8
5/5/6
-/-/-
-/-/-
-/-/-
-/-/-
4 / 10 / 5
4/2/7
-/1/2
-/-/-
-/-/-
-/-/-
6 / 11 / 7
2/2/6
-/-/-
-/-/-
-/-/-
-/-/-
6/4/5
-/5/4
2/3/4
-/1/-
-/-/1
-/-/-
6 / 10 / 7
2/3/6
-/-/-
-/-/1
-/-/-
-/-/-
3/4/2
5/3/5
-/4/5
-/2/-
-/-/1
-/-/1
4 / 13 / 4
4/-/9
-/-/1
-/-/-
-/-/-
-/-/-
5/7/4
3/4/9
-/2/-
-/-/-
-/-/1
-/-/-
Question 1: it was determined that 100% of students for both first and second year, and 93% of students for third year
agreed at some level that the course was useful in improving their overall knowledge and skills in electrical engineering
65
applications. As can be seen in Table 4, Year 2 implementation with the highest mean and lowest standard deviation
definitely was perceived as best by the students. This result can be attributed to the benefit of extensive topics coverage
and assessment strategies (on-line and in-class) used in Year 2.
Question 2: when asked if mathematical relationships selected were appropriate and useful, 100% of the respondents for
all three years strongly agreed or agreed. Year 2 implementation has again the highest mean, median and lowest standard
deviation which are the indicators of better student perception. This result can be attributed to the benefit of Year 2’s
extensive in-class assessments, where mathematical relationships were commonly introduced.
Table 4: Student survey statistical analysis.
1
Mean
Year
2
1
Median
Year
2
3
3
4.63
4.69
4.50
5
5
5
0.52
0.48
0.65
4.38
4.62
4.57
4
5
5
0.52
0.51
0.51
4.50
4.69
4.21
4.50
5
4
0.50
0.63
0.70
4.75
4.85
4.54
5
5
5
0.46
0.38
0.52
4.50
3.92
3.86
5
4
4
0.93
0.95
1.17
4.75
4.77
4.36
5
5
4.50
0.46
0.44
0.84
4.38
3.69
3.54
4
4
4
0.52
1.11
1.05
4.50
5
4.21
5
5
5
0.50
0
0.58
4.63
4.38
4.07
5
5
4
0.52
0.77
1.00
Survey question
1. Have you found the course
useful to improve your
knowledge and skills on overall
electrical engineering
applications?
2. Are mathematical relationships
and calculations selected in this
course appropriate?
3. Are the computational
simulation tools (PSpiceTM)
selected appropriate?
4. Do you think power electronics
would be a good tool to promote
science, technology and
engineering majors among
college students?
5. Do you think you are interested
to work in electrical power
related industry after your
graduation?
6. Overall quality of instruction
was appropriate and useful for
this class.
7. Pre-recorded lecture videos
along with interactive face to
face instruction are effective
ways to deliver course materials
and helped my understanding.
8. On-line and in-class quizzes
before and after the lecture
appropriately assessed and
improved my understanding.
9. I am interested in enrolling in
future courses of similar subject
matters.
Standard deviation
Year
1
2
3
Question 3: when asked if the computational tool selected (PSpiceTM) was appropriate, 100% of the respondents in Year
1 strongly agreed or somewhat agreed. This percentage dropped to 92.3% for Year 2 students and 85.7% for Year 3
students. However, the statistical analysis for this question in Table 4 reveals mixed results. Year 2 implementation has
the best mean and median, but larger standard deviation than Year1. PSpiceTM simulations were part of homework
assignments and in-class tests for all years that required computer usage. The only difference in implementation was
slightly reduced number of PSpiceTM assignments in Year 2 in comparison to Year 1. Year 3 results had the worst scores
for all three statistical metrics, which could possibly be due to the least exposure to PSpiceTM assignments.
Although it is difficult to attribute these results to the specific implementation, one can generally conclude that PSpiceTM
is an appropriate computational tool for the course.
Question 4: in terms of promoting STEM majors through Power Electronics, both Year 1 and Year 2 students had the
highest strongly agree percentage among all questions. For Year 3 students, this result was the second best after the
survey Question 2. The statistical analysis in Table 4 confirms this result. The Year 2 implementation was again
66
perceived best by the students, which is statistically proven by higher mean and lower standard deviation metrics. This
result can be attributed to the benefit of extensive topics coverage and exposure to various assessments (on-line and inclass) used in Year 2.
Question 5: the first year respondents showed definitely the greatest interest working in the electrical power related
industry with a strongly agree percentage of 75% and Year 3 students showed the least interest working for the industry
based on the statistical metrics in Table 4. Although the second and third year respondents had also reasonably well and
similar interest working in the industry, their overall average response score for both mean and median metrics was
substantially lower than Year 1 as shown in Table 4. The more challenging nature of Year 2 and Year 3 implementation
might possibly be a contributing factor for these results.
Overall standard deviations in this question was the largest in comparison to the other questions. It should be
emphasised that this was a required course for all EE majors.
Question 6: concerning quality of instruction, both Year 1 and Year 2 students had one of the largest strongly agree
responses and one of the lowest standard deviations. Among Year 3 students, this was one of the top four scores. This
question yielded closest scores between the first and second year respondents. Although Year 2 implementation yielded
slightly better statistics, the spread is not large enough to derive a conclusion. The same faculty member teaching the
course for both years is likely to be a contributing factor. Year 3 scores for all metrics were the lowest possibly due to
the coverage of the least number of topics and assignments that tend to enhance the learning experience.
Question 7: concerning the use of pre-recorded lectures, students provided the most diverse responses when comparing
first year to either second or third year survey participants. As mentioned earlier, the second and third year
implementation regularly required students to watch pre-recorded on-line lecture videos. Surprisingly, only about half
of the class agreed on the benefit of the hybrid (or partially) flipped lecture approach. Although the first year
respondents were only informed and not really instructed to watch these pre-recorded lectures, 100% of students agreed
at some level on the benefit of the hybrid approach, which was much less emphasised and experienced in this year. The
statistics in Table 4 details these results.
The mean and median for Year 1 and Year 3 are among the lowest scores in similar statistics for Question 1 through 9;
however, the standard deviation for Year 1 is moderate. The standard deviation for Year 3 is second largest after Question
5. For Year 2, all statistics are in the extremes meaning lowest mean and median and highest standard deviation for all
questions. These statistics revealed that there is a delicate balance between pre-recorded and in-class lecture combination
that students like to see and regularly emphasised/instructed on-line lectures were not perceived well.
Question 8: concerning on-line and in-class quizzes during class time, the second year respondents unanimously strongly
agreed to the benefit of this approach to improving their understanding of the course material. This was overall the best
evaluation by the students. The number of quizzes in the first year was substantially less than that of the second and the
third year. The level of agreement on the benefit was still quite positive, but definitely lower than the second year. In
the third year, the quiz management structure was similar to that of Year 2 and the scores were neither as good as Year 2
nor Year 1. However, for Year 3, on-line and in-class quiz mix were definitely perceived better than pre-recorded online lecture and in-class lecture mix. It should be emphasised that the instructor preparation and evaluation time for these
quizzes was quite intense, especially, in the second and third year.
These results showed that emphasised hybrid on-line/in-class assessment approach was well received by the respondents as
opposed to the results of Question 7 where less emphasised hybrid on-line/in-class lecture approach was perceived well.
Question 9: the first year respondents showed definitely the greatest interest in enrolling in future courses of similar
subject matters. Although the second year respondents also had a reasonably strong interest in enrolling in the future
courses, their overall average response score for mean metric was lower, as shown in Table 4. The least interest came
from the third year respondents. The statistical metric trends in this question were similar to those for Question 5 where
students’ future interest in power related industry was inquired.
It should also be noted that the second and third year respondents were larger and more diverse populations as
mentioned earlier, and a one-to-one comparison among these populations may not always be informative.
In general, the survey responses among all respondents were somewhat close in a majority of the questions. The greatest
separation between first and second year surveys occurred in Questions 5, 7 and 8. The greatest separation between first
and third year surveys occurred in Questions 5, 7 and 9. Finally, the greatest separation between second and third year
surveys occurred in Questions 3, 8 and 9.
From the instructor’s perspective, Year 2 and 3 implementations were definitely more costly in terms of time and effort
for emphasised on-line/in-class lecture/assessment approaches. The survey definitely showed the effectiveness of hybrid
assessment approach of Year 2 and 3, and hybrid lecture approach of Year 1.
67
The overall mean score for Year 1 and Year 2 was in the range of 4.5, with the first year having a slightly better score.
The overall mean score for Year 3 was approximately 4.2, which is possibly due to the smaller level of interest in power
related fields. The return investment for this course was verified when more than two thirds of all students over the three
year period expressed an interest in working in the electrical power industry after graduation.
The average grade on all assignments for all students in the course was A- in the first year, B in the second year and B+
in the third year. The greater course load due to substantially increased amount of quizzes and extensive topics coverage
is likely to play a role in the lowest average grade in the second year. The distribution of grades on all assignments
followed a fairly normal distribution in all years. In general, students excelled on the on-line concept quizzes.
Additional Course Assessment Results for Year 3
The Year 3 survey included two additional questions to help differentiate effective lecture methodology. Table 5
summarises these results.
Table 5: Additional survey results for Year 3.
Survey question
1. Pre-recorded lecture videos alone is an
effective way to deliver course materials
and helped my understanding?
2. Interactive face-to-face instruction alone is
an effective way to deliver course
materials and helped my understanding?
Strongly
agree
Agree
Neutral
Disagree
Strongly
disagree
Not
applicable
1
2
3
5
2
1
3
7
4
These results combined with Question 7 of Table 3 yield the following common statistical metrics. In Table 6, the
statistical results shown in hybrid column represent Question 7 of Table 3, the ones in on-line column represent
Question 1 of Table 5, and the ones in face-to-face column represent Question 2 of Table 5.
Table 6: Student perceptions of learning: lecture delivery related survey statistics for Year 3.
Mean
Median
Standard deviation
Hybrid
On-line
Face-to-face
Hybrid
On-line
Face-to-face
Hybrid
On-line
Face-to-face
3.54
2.62
3.93
4
2
4
1.05
1.19
0.73
The metrics in Table 6 clearly reveal that the preferred method of lecture delivery for the third year participants is
face-to-face.
CONCLUSIONS
In this article, a hybrid flipped classroom approach to teaching Power Electronics for three consecutive years at Western
Carolina University has been presented. The study analysed lecture and quiz elements of instruction for on-line and/or
face-to-face implementation. According to the survey results, the students in general were motivated and greatly
benefited from this hybrid approach. The survey results showed that:
1.
2.
3.
In the first year, in which a hybrid mix heavily emphasised the face-to-face component, students felt that the extra
in-class lectures helped improve their understanding.
In the second and the third year, in which a hybrid mix heavily emphasised the on-line component, students felt
that the increased number of on-line and in-class assessments really helped improve their understanding. Students
felt that the extra on-line lectures did not significantly improve their understanding.
Additional survey questions in the third year revealed that students prefer face-to-face instructions over hybrid or
on-line instruction.
This study shows that combining on-line and face-to-face elements are important as suggested by the US Department of
Education (DOE) report [10]. However, the level of combination at the right amount is critical to improve student
perception of learning. This course aims to address the emerging needs of the society at the same time when addressing
the needs of students with diverse backgrounds and demographics. The assessment results show that the synchronised
quizzes tied to specific course modules enhanced student comprehension.
As a next step, the course is projected to be offered with the combination of on-line and face-to-face elements as
suggested above. In addition, it is also planned to develop in-class laboratory demonstration activities for further
understanding and analysis of the subject matter.
68
REFERENCES
Center for Energy Workforce Development, Gaps in the Energy Workforce Pipeline - 2011 CEWD Survey Results
(2011), 07 June 2015, www.cewd.org/surveyreport
2. North American Electric Reliability Council, 2008 Long-term Reliability Assessment: To Ensure the Reliability of
the Bulk Power System (2008), 07 June 2015, http://www.nerc.com/files/LTRA2008v1_2.pdf
3. Sergeyev, A. and Alaraje, N., Industry-driven power engineering curriculum development in electrical and
computer engineering technology program, Proc. American Society for Engng. Educ. Conf. (2011).
4. Karayaka, H.B. and Adams, R., A project based implementation of a power systems course for electrical and
computer engineering technology students, Proc. American Society for Engng. Educ. Conf. (2013).
5. Mousavinezhad, S.H., Schlesinger, T.E., Lightner, M.R., Smith, M.J., Roy, L., Sullivan, B.J., Venkata, S.S. and
Kuh, A., Electric energy and power educational programs development workshop, Proc. American Society for
Engng. Educ. Conf. (2011).
6. University of Minnesota, Electric Energy Systems - Education and Research (2014), 07 June 2015,
http://www.ece.umn.edu/groups/power/.
7. Lin, J-L., Imbertson, P. and Moore, T., Introducing an instructional model in undergraduate electric power energy
systems curriculum - Part (I): authoritative vs. dialogic discourse in problem-centered learning. Proc. American
Society for Engng. Educ. Conf. (2013).
8. Lin, J-L., Imbertson, P. and Moore, T., Introducing an instructional model for flipped engineering classrooms Part (II): how do group discussions foster meaningful learning?, Proc. American Society for Engng. Educ. Conf.
(2014).
9. Alexander, R., Culture, dialogue and learning: notes on an emerging pedagogy, education, culture and cognition:
intervening for growth. Proc. Inter. Association for Cognitive Educ. and Psychology (IACEP), 10th Inter. Conf.,
(2005).
10. Mean, B., Toyama, Y., Murphy, R., Bakia, M. and Jones, K., Evaluation of evidence-based practices in on-line
learning: a meta-analysis and review of on-line learning studies, (2009), 07 June 2015,
http://eric.ed.gov/?id=ED505824
11. Karayaka, H.B. and Adams, R., A hybrid flipped classroom approach to teaching power electronics to electrical
engineering students. Proc. American Society for Engng. Educ. Conf. (2015).
1.
BIOGRAPHIES
Hayrettin Bora Karayaka received his BS and MS degrees in Control and Computer
Engineering from Istanbul Technical University (Istanbul, Turkey), in 1987 and 1990,
respectively, and his PhD degree in Electrical Engineering from the Ohio State University
(Columbus, OH, USA), in 2000. Dr Karayaka is currently an Assistant Professor in the
Department of Engineering and Technology at Western Carolina University. He is responsible
for teaching electric power engineering courses in the Department. He previously held a faculty
appointment at Texas A&M University-Corpus Christi (Corpus Christi, TX, USA) between
2009 and 2012. Dr Karayaka also worked as a senior engineer for smart grid and wireless
communication industries in the USA for over ten years. Dr Karayaka has published research
papers primarily in the areas of power engineering education, ocean wave energy,
identification, modelling and control for electrical machines, and smart grid.
Robert Adams is an Associate Professor in the Department of Engineering and Technology
at Western Carolina University. He has nine years of industrial experience as an electrical
engineer in the area of analysis and testing of RF communications equipment and 21 years of
teaching experience in engineering and technology undergraduate programmes. His research
interests include digital image processing, biomedical signal processing and engineering
education. Dr Adams holds PhD, MS and BS degrees in Electrical Engineering from the
University of Alabama in Huntsville, Johns Hopkins University, and Clarkson University,
respectively.
69